The present invention relates to apparatus for forming sheet metal parts, especially where only one or a few parts of complex contour are to be produced.
Many sheet metal parts are made of die forming a sheet metal blank to a complex three-dimensional curved surface. This requires the use of dies, or die sets, which must be very accurately made, and the workpiece is placed between male and female dies and formed to the desired shape by stamping or pressing. The making of such dies with the necessary dimensional accuracy is a difficult and exacting process, requiring highly skilled tool and die makers and much time. The cost of the dies is correspondingly high. When a large number of identical parts is to be made, the cost of the dies is acceptable, but when only one or a few parts are to be made, the cost of the dies becomes expensive and is frequently prohibitive. In some cases, a female die only can be used with such techniques as explosion forming, but this is not always satisfactory and still involves the cost of at least one die. In some cases, it has been possible to approximate the desired complex curves by a series of straight bends on a standard bending machine; while in other cases, a wooden or metal die may be prepared and the sheet metal part hand-formed around the die. Some parts may be hand-formed without dies with suitable tools by sufficiently skilled craftsmen. All of these expedients, however, either compromise the design, that is, undesirably change or modify the desired configuration, or require the use of highly skilled and expensive labor, or both, so that they do not represent satisfactory solutions to the problem.